Should I use my Blu-ray player to upscale my movies to 4K, or should I keep the player in standard HD mode and let my DLA-RS57 upscale to 4K? What about receivers that upscale HD to 4K?

In most cases, your DLA-RS57 will do a better job of upscaling HD video than external devices or sources that have a 4K upscaling option. This should be true with all JVC projectors with the 4K e-shift feature. No matter how you configure your system, make sure you only use certified high speed HDMI cables.